In the past, the relative motion of the antenna during its normal sweep and the target, has caused a degradation in the receiver gain and therefore a reduction in the weather detection capabilities of typical airborne weather radar. Previous airborne weather radar systems have included local oscillators which have demonstrated problems in providing tunability over a wide range and yet exhibiting sufficiently low phase noise to eliminate interference with the turbulence detection function of modern weather radar systems.
Consequently, there exists a need for improvement in airborne weather radar systems which are able to compensate for the variable Doppler shift, caused by the forward motion of the aircraft and the relative motion of the antenna sweep; while concomitantly allowing for turbulence detection of a raindrop.